Embedding hidden information in styled text

Question

I would like to convert a collection of digitized documents to Mathematica notebooks. They are formatted as XML, divided into pages. The XML contains formatting I would like to preserve, but I do not want to display page divisions, in other words I would like the text to flow like a typical notebook. However, I would like to use a docked cell to display the page range of any text that is selected. A text selection could come from a single page or multiple pages.

My question is, what is the best way to represent this data? I imagine StyleBoxes and TagBoxes (to hold page numbers) but I don't have a clear understanding of how these interact. When I try to nest one inside the other (TaxBox[StyleBox[...]] or StyleBox[TagBox[...]]) I end up with cells that just print as expressions. I also imagine I could use InterpretationBoxes to store the formatted text and then a hidden duplicate copy with the page information added, but that is so inefficient I have to believe there is a better way.

Here's an example. What would be a good way to represent this text? Say it spans pages 1-2, divided at ///.

A sentence that spans two /// pages and has some mixed formatting.

EDIT:

The following code almost works, but the way it behaves when I try to select text with my mouse is off.

Cell[BoxData@RowBox[{
 TagBox[RowBox[{
    StyleBox["A sentence", "Text"],
    StyleBox["that spans two", "Text", FontWeight -> "Bold"]
    }], "Page1"],
 TagBox[RowBox[{
    StyleBox["pages", "Text", FontWeight -> "Bold", 
     FontSlant -> "Italic"],
    StyleBox["and has some mixed formatting.", "Text"]
    }], "Page2"]
 }]] // CellPrint

If I place the cursor on the left side of this sentence and drag toward the right, once I pass "two" the entire right-side box becomes selected. So, for example, I cannot select "two pages" using my cursor. I understand this is related to the hierarchical nature of the underlying expressions; is there something that can be done about it? Or is there an alternative representation that will avoid this problem?

Answer 1

Dummy styles appear to be an excellent technique for storing such information without affecting front-end selection behavior.

Cell[BoxData@StyleBox[#, "Text"] &@RowBox@{
 StyleBox[RowBox@{
    "A sentence",
    StyleBox["that spans two", FontWeight -> "Bold"]
    }, "Page1"],
 StyleBox[RowBox@{
    StyleBox["pages", FontWeight -> "Bold", FontSlant -> "Italic"],
    "and has some mixed formatting."
    }, "Page2"]
 }] // CellPrint

More idiomatically,

Notation[page[box_,n_] \[DoubleLongLeftRightArrow] StyleBox[box_,"Page"~~ToString[n_]]]

Cell[BoxData @ StyleBox[#,"Text"]& @ RowBox @ {
 page[#,"1"]& @ RowBox @ {
   "A sentence",
   StyleBox["that spans two",FontWeight->"Bold"]
  },
 page[#,"2"]& @ RowBox @ {
   StyleBox["pages",FontWeight->"Bold",FontSlant->"Italic"],
   "and has some mixed formatting."
  }
}]//CellPrint